Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors, and in particular, complementary metal-oxide-semiconductor (“CMOS”) image sensors, has continued to advance at great pace. For example, the demands of higher resolution and lower power consumption have encouraged the further miniaturization and integration of these image sensors.
Conventional CMOS image sensors use color filter arrays such as red, green, and blue (RGB), arranged in what is known as a Bayer pattern. In addition, clear pixels, also known as panchromatic pixels, may be included in the color filter array in order to increase the sensitivity of the image sensors. A color filter array that includes clear pixels in addition to the RGB color filters may be referred to as being arranged into an RGBC pixel pattern.
However, some RGBC patterns may suffer from color aliasing. Color aliasing refers to the effect of the wrong color appearing in an area of the image. For example, a color such as red or blue may be seen in an area that should be green. Color aliasing occurs at least partly due to the alignment of the clear filters within the RGBC pattern. Image sensors with clear pixels are more prone to color aliasing since clear pixels do not produce any color information of their own other than the intensity of light.